The present invention relates to a workpiece feeder device for a traveling gripper means in a sewing unit.
As is well known, the aforementioned gripper means is used to grip superimposed pieces of fabric constituting the workpiece to be sewn to keep the edges matched together and also to keep them on the sewing surface of the unit as the workpiece is moved towards the sewing machine.
It is necessary for the pieces of fabric to be gripped in this way for various reasons, for example, because of pattern defects, as a result of preceding sewing operations, and also as a result of the fact that the pieces of fabric are cut in large numbers at one time using suitable cutting means. As a result of these defects, differences occur in the dimensions of the pieces of fabric which make it necessary to match the pieces correctly after suitable tensioning to make the two pieces the same length. Thereafter, the pieces of fabric which have been correctly positioned one on top of the other in the aforementioned manner are gripped by the gripper means and inserted beneath the presser foot of the sewing machine.
Gripper devices are already known wherein the traveling gripper means moves freely on the sewing surface to accompany the workpiece as it is being sewn.
Quite obviously, when devices of the above type are used, the operator must wait until the traveling gripper means returns to its starting position before a fresh workpiece can be gripped.
The object of the present invention is to improve the features of the above-mentioned known devices by providing means which are designed to eliminate the aforementioned waiting time which unfavorably influences the entire operating cycle of the sewing unit. The technical problem to be solved is that of employing the translational movement of the traveling gripper means towards the sewing machine and its return movement towards the position where the workpieces are gripped, for the purpose of placing a fresh workpiece in a position in which it can be gripped by the gripper means when the latter returns to its starting position.